The invention pertains to a closing mechanism for the mold halves of an individual section (I.S.) machine.
Such a closing mechanism for use on the blank molds of an I.S. machine is known, for example, from DE 33 466 C2. In this case, two mold holders designed for respectively carrying three mold halves are provided, wherein one end of a crank arm, the other end of which is connected to a drive shaft, is respectively supported on the upper ends of said mold holders, and wherein oppositely directed rotational motions of the two drive shafts are realized by means of the vertically extending piston rod of a pneumatically actuated piston-cylinder unit arranged in a lateral housing and an intermediate arrangement of transmission levers. The activation of the piston-cylinder unit makes it possible to move the mold halves between an open and a closed position of the closing mechanism, namely along an arcuate transfer curve that slightly raises the mold halves, wherein connecting rods are provided along the transfer curve in order to preserve the parallel alignment of the oppositely arranged mold halves relative to one another, and wherein said connecting rods respectively form a parallel linkage for guiding each of the two mold holders together with the aforementioned crank arms. The transfer curve is designed in such a way that two respectively adjoining mold halves are starting from the closed position abruptly separated from an upwardly extending neck shape when an opening motion is initiated, wherein this measure is intended to reduce the wear. Some of the components designed for converting the linear motion of the aforementioned piston rod into symmetric, oppositely directed rotational motions of the two drive shafts protrude from the underside of the housing. A duct system equipped with a valve makes it possible to act upon the regions behind the mold halves and within the mold holders with cooling air.
DE 26 23 106 B2 discloses another closing mechanism, in which the transfer curve of the mold halves is in contrast to the object of DE 33 46 466 C2 realized linearly. For this purpose, mold carrier halves are respectively arranged such that they can be displaced between a closed and an open position by means of compressed air motors along parallel guide rods rigidly arranged on the machine. A gear mechanism with a comparatively complex design characterized by an articulately connected lever is located between the compressed air motors and the mold carrier halves. The closing mechanism proposed in this publication is equally suitable for use in blank molds and finishing molds of a glass forming machine.
These known closing mechanisms are characterized by a complex mechanical design of the connection between the mold holders and the drive used. Due to the plurality of transmission elements, it is particularly difficult to realize a largely backlash-free connection. In addition, the installation of an effective cooling system for preventing thermally related stresses, particularly between mold holder and machine base body, is not sufficiently taken into account.
EP 2 230 217 A1 discloses a closing mechanism for the blank mold halves of an IS glass forming machine, in which two blank mold holders are linearly guided toward one another and apart from one another in a parallel fashion on a common guide shaft such that both blank mold holders can be simultaneously transferred into an open or a closed position. The guide shaft extends on one side of the two blank mold holders. The disadvantage of this concept can be seen in that it is impossible to realize a symmetric force transfer to the multiple blank molds that are held by the blank mold holders during the glass forming process.
US 2005/0005647 A1 discloses an inverting mechanism for transferring parisons from the blank mold side of a glass forming machine to a finish mold side, wherein said inverting mechanism is combined with a closing mechanism for opening and closing the neck ring arms designed for taking hold of the parisons. For this purpose, a spindle shaft with two oppositely oriented thread sections carrying respective spindle nuts is provided, wherein said thread sections are respectively connected to a neck ring arm designed for holding a parison. The threaded spindle can be driven in an oscillating fashion between an open and a closed position of the neck ring arms and therefore linearly in the axial direction of the spindle shaft by means of a first servomotor. A ball spline shaft extends coaxial to and surrounds the threaded spindle and is respectively connected to the neck ring arms by means of a ball key nut, wherein the ball spline shaft can be driven by means of a second servomotor independently of the first servomotor in order to realize a pivoting motion of the neck ring arms between a position facing the blank mold side and a position facing the finishing mold side about the axis of the spindle shaft. This publication does not contain any information on the design of a closing mechanism of the blank molds that is active during a glass forming process.
U.S. Pat. No. 4,652,291 A discloses another closing mechanism for opening and closing the neck ring arms of an inverting mechanism, wherein this closing mechanism has a design comparable to that of the object of the latter-mentioned publication and is structurally combined with said inverting mechanism.
WO 2010/102590 A2 discloses another comparable closing mechanism for the blank molds or finishing molds of a glass forming machine, in which the mold holder halves are supported on linear guides such that they can be displaced between an open and a closed position. The guide is formed by a first rod of circular cross section that extends on one side of the mold holder halves at a height that approximately corresponds to half the height of the mold holder halves, wherein a second rod of rectangular cross section, which is accommodated in a U-shaped profile and extends along the bottom region of the mold holder halves parallel to the first rod, is arranged opposite of this first rod on the opposite side of the mold holder halves. An independent drive is assigned to each of the mold holder halves and connected to the respective mold holder half by means of a cam and a sliding block guided in a groove.
This known closing mechanism is characterized by a respective punctiform transmission of the closing force to the mold holder halves, namely at a distance from the guide. In addition to an uneven distribution of the closing force over the mold holder halves, a tilting motion of the mold holder halves on the guides cannot be ruled out in this case.